parr ut,] THE MECHANISMS OF FLOWERS. 503 
majority, Plectranthus, Ocymum, Salvia patens, etc., being - ex- 
ceptions to it. (6) Dichogamy has been shown above to be far 
from universal : Ajuga, Lamium, Galeopsis, and others are homo- 
gamous, and even in the majority of the others dichogamy is 
not so complete as to prevent self-fertilisation. Self-fertilisation 
seems to be rendered impossible only in the species, of Nepeta, 
Thymus, Mentha, and Salvia described above. 
In regard to the imsects which the Labiatz have adapted 
themselves to, the forms which I have described show a re- 
markable series of gradations, the visitors being more and more 
restricted as the length of the corolla-tube increases. 
The short-tubed flowers of Mentha and Lycopus are visited 
chiefly by flies and also by insects of various other orders. In 
Thymus and Origanum, in addition to flies, bees come more and 
more to the front, though insects of other orders take a certain share ; 
in Betonica bees and flies are of about equal importance as fer- 
tilisers; in Stachys palustris and S. silvatica bees are very much 
the most important visitors, and in Lavendula, Salvia, Galeobdolon, 
Lamium, Galeopsis, Ballota, Teucrium, and Ajuga bees perform 
almost all the work of fertilisation, though Lepidoptera and 
long-tongued flies are not excluded. 
Orv. PLANTAGINEZ. 
367. PLANTAGO LANCEOLATA, L.—Delpino (567) distinguishes 
three forms of this species :— 
“One form,” he says, “with a strong and very tall scape, and very broad, 
white anthers which quiver in the wind, grows in meadows and is exclusively 
anemophilous, for I have never seen it visited by insects. The second form 
grows on the hills, and has a much shorter scape ; it also is essentially anemo- 
philous ; I once saw a species of Halictus on a spike, trying to gather pollen ; 
but the structure of the flower is so unfitted for pollen-collecting, that great 
part of the pollen fell to the ground without benefiting either the plant or the 
insect. Finally, the third form is dwarfish and confined to the mountains ; 
it has the shortest spikes and filaments ; on meadows in the Apennines at 
Chiavari I have seen bees in numbers flying from one flower to another of this 
variety, collecting the pollen and performing cross-fertilisation. 
‘This therefore is a form of Plantago which hangs between the anemo- 
philous and entomophilous conditions, and is capable of being fertilised equally 
well by the wind and by bees. If the filaments became stiff and coloured and 
the pollen-grains adhesive while the anthers lost their peculiar quivering, 
we should have before us the passage from anemophilous to entomophilous 
characters, the evolution of an entomophilous from an anemophilous species. _ 
“This hypothetical transition has actually occurred. Plantago media is a 
